Coordinated Site Network for Studying the Impacts of 4R Nutrient Management on Crop Production and Nutrient Loss

Currently, there is a concerted effort from industry, universities, and state and federal action agencies to promote the 4R nutrient management approach on-farm– considering the Right source, Right rate, Right time, and Right place– for managing nutrient additions from commercial fertilizer and organic materials.

With its massive acreage and intensive nutrient use, corn production systems are an important focus of the 4R program. To convince farmers to adopt the 4R approach, and to ensure that production, soil health, and environmental goals are realized, there is a critical need for field research that measures responses to 4R management systems across a range of soils and agro-ecosystems within the main corn producing areas of North America. Limited research data linking agronomic and environmental performance of 4R practices across a wide variety of conditions is a critical research gap leading to high uncertainty regarding practice efficacy for both farmers and environmental program and policy decision makers. Along with production and soil health effects, full accounting of the multiple forms and pathways of nitrogen (N) and phosphorus (P) is essential to understand the environmental consequences of current and advanced best nutrient practices.

A thorough accounting of the N balance could also serve as an early warning for practices that are improving or reducing soil carbon and thus soil health because soil carbon-nitrogen interactions dramatically impact soil organic matter accumulation and carbon sequestration. Further, potassium (K) nutrition of crops has attracted renewed attention, and although not of environmental concern, K requirements of crops are nearly the same as those of N, and cannot be ignored. We propose the creation of a coordinated field site network strategically distributed across the cornbelt with unique infrastructure that would collect similar agronomic and environmental measures thereby enabling for the first time knowledge synthesis across varied soils, climates, and management systems. Quantification of the impacts of 4R management on crop yield, P, K, and nitrate (NO3) losses in water, N losses to the atmosphere, and changes in soil health at the same location under a range of management practices is severely lacking. In addition, we are aware of no studies explicitly aimed at understanding the interactions between 4R management strategies and soil health.